A grain-oriented electrical steel sheet is a steel sheet that contains Si and of which the orientation of crystal grains is highly integrated in the {110}<001> orientation, and is used as a material of a wound iron core and so on of a stationary induction apparatus such as a transformer. The control of the orientation of the crystal grains is performed by using an abnormal grain growth phenomenon called secondary recrystallization.
In recent years, there has been a growing tendency to save energy, so that as a method to achieve the above secondary recrystallization, the following manufacturing techniques have been established. In Patent Literature 1, there has been disclosed a low-temperature slab heating method in which based on heating a slab at a temperature of 1280° C. or lower, in a nitridation annealing step performed after cold rolling, fine dispersed precipitates such as AlN, (Al.Si)N being inhibitors are precipitated.
Further, there has been known a method of containing an auxiliary element that strengthens the function of inhibitors in a grain-oriented electrical steel sheet, in order to improve a magnetic property of a product. A method of utilizing Te as the element as above has been disclosed in Patent Literatures 2 to 5.
However, when Te is contained in the grain-oriented electrical steel sheet, the magnetic property of a product is improved, but there is caused a problem that a defect is caused on an appearance of a glass coating film existing on the surface of the grain-oriented electrical steel sheet.